<!-- 登录页 -->
<script>
    import { beforeUpdate } from "svelte";

    import { router } from "../routes";
    import { login } from "../api/login";
    import { loginUser } from "../utils/stores";

    import { Snackbar, Button } from "svelte-mui/src";

    let errAlertVisible = false;
    let errAlertMsg = "error";
    let okAlertVisible = false;
    let okAlertMsg = "success";

    let username = "";
    let password = "";

    // 登录过就不再出现登录页
    beforeUpdate(() => {
        if ($loginUser.nickname) {
            router.push("/admin/index");
        }
    });

    // 点击按钮提交登录
    const loginBtnClick = () => {
        if (username == "" || password == "") {
            errAlertMsg = "请输入用户名和密码";
            errAlertVisible = true;
            return;
        }
        window.sessionStorage.setItem("nickname", '超级无敌大帅哥');
        window.sessionStorage.setItem("token", 'dghffbd65gnbvdwe7565t4rtthng');
        router.push("/admin/index");
    };
    
</script>

<Snackbar
    color="#f56c6c"
    bg="#fef0f0"
    bind:visible={errAlertVisible}
    timeout={1}
    style="height: 30px; border-radius: 4px;"
>
    {errAlertMsg}
    <span slot="action">
        <Button
            color="#a8abb2"
            on:click={() => {
                errAlertVisible = false;
            }}>✕</Button
        >
    </span>
</Snackbar>
<Snackbar
    color="#67c23a"
    bg="#f0f9eb"
    bind:visible={okAlertVisible}
    timeout={1}
    style="height: 30px; border-radius: 4px;"
>
    {okAlertMsg}
    <span slot="action">
        <Button
            color="#a8abb2"
            on:click={() => {
                okAlertVisible = false;
            }}>✕</Button
        >
    </span>
</Snackbar>

<section>
    <!-- 背景颜色 -->
    <div class="color" />
    <div class="color" />
    <div class="color" />
    <div class="box">
        <!-- 背景圆 -->
        <div class="circle" style="--x:0" />
        <div class="circle" style="--x:1" />
        <div class="circle" style="--x:2" />
        <div class="circle" style="--x:3" />
        <div class="circle" style="--x:4" />
        <!-- 登录框 -->
        <div class="container">
            <div class="form">
                <h2 style="font-size: 26px;">登录</h2>
                <form>
                    <div class="inputBox">
                        <input
                            type="text"
                            placeholder="用户名"
                            bind:value={username}
                        />
                    </div>
                    <div class="inputBox">
                        <input
                            type="password"
                            placeholder="密  码"
                            bind:value={password}
                        />
                    </div>
                    <div class="inputBox" style="ma">
                        <input
                            type="button"
                            value="登录"
                            on:click={loginBtnClick}
                        />
                    </div>
                </form>
            </div>
        </div>
    </div>
</section>

<style>
    /* 使用flex布局，让内容垂直和水平居中 */
    section {
        /* 相对定位 */
        position: relative;
        overflow: hidden;
        display: flex;
        justify-content: center;
        align-items: center;
        min-height: 100vh;
        /* linear-gradient() 函数用于创建一个表示两种或多种颜色线性渐变的图片 */
        background: linear-gradient(to bottom, #f1f4f9, #dff1ff);
    }

    /* 背景颜色 */
    section .color {
        /* 绝对定位 */
        position: absolute;
        /* 使用filter(滤镜) 属性，给图像设置高斯模糊*/
        filter: blur(200px);
    }

    /* :nth-child(n) 选择器匹配父元素中的第 n 个子元素 */
    section .color:nth-child(1) {
        top: -350px;
        width: 600px;
        height: 600px;
        background: #ff359b;
    }

    section .color:nth-child(2) {
        bottom: -150px;
        left: 100px;
        width: 500px;
        height: 500px;
        background: #fffd87;
    }

    section .color:nth-child(3) {
        bottom: 50px;
        right: 100px;
        width: 500px;
        height: 500px;
        background: #00d2ff;
    }

    .box {
        position: relative;
    }

    /* 背景圆样式 */
    .box .circle {
        position: absolute;
        background: rgba(255, 255, 255, 0.1);
        /* backdrop-filter属性为一个元素后面区域添加模糊效果 */
        backdrop-filter: blur(5px);
        box-shadow: 0 25px 45px rgba(0, 0, 0, 0.1);
        border: 1px solid rgba(255, 255, 255, 0.5);
        border-right: 1px solid rgba(255, 255, 255, 0.2);
        border-bottom: 1px solid rgba(255, 255, 255, 0.2);
        border-radius: 50%;
        /* 使用filter(滤镜) 属性，改变颜色。
    hue-rotate(deg)  给图像应用色相旋转 
    calc() 函数用于动态计算长度值 
    var() 函数调用自定义的CSS属性值x*/
        filter: hue-rotate(calc(var(--x) * 70deg));
        /* 调用动画animate，需要10s完成动画，
    linear表示动画从头到尾的速度是相同的，
    infinite指定动画应该循环播放无限次*/
        animation: animate 10s linear infinite;
        /* 动态计算动画延迟几秒播放 */
        animation-delay: calc(var(--x) * -1s);
    }

    /* 背景圆动画 */
    @keyframes animate {
        0%,
        100% {
            transform: translateY(-50px);
        }
        50% {
            transform: translateY(50px);
        }
    }

    .box .circle:nth-child(1) {
        top: -50px;
        right: -60px;
        width: 100px;
        height: 100px;
    }

    .box .circle:nth-child(2) {
        top: 150px;
        left: -100px;
        width: 120px;
        height: 120px;
        z-index: 2;
    }

    .box .circle:nth-child(3) {
        bottom: 50px;
        right: -60px;
        width: 80px;
        height: 80px;
        z-index: 2;
    }

    .box .circle:nth-child(4) {
        bottom: -80px;
        left: 100px;
        width: 60px;
        height: 60px;
    }

    .box .circle:nth-child(5) {
        top: -80px;
        left: 140px;
        width: 60px;
        height: 60px;
    }

    /* 登录框样式 */
    .container {
        position: relative;
        width: 400px;
        min-height: 400px;
        background: rgba(255, 255, 255, 0.1);
        display: flex;
        justify-content: center;
        align-items: center;
        backdrop-filter: blur(5px);
        box-shadow: 0 25px 45px 8px rgba(0, 0, 0, 0.1);
        border: 1px solid rgba(255, 255, 255, 0.5);
        border-radius: 4px;
        border-right: 1px solid rgba(255, 255, 255, 0.2);
        border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    }

    .form {
        position: relative;
        width: 100%;
        height: 100%;
        padding: 50px;
    }

    /* 登录标题样式 */
    .form h2 {
        position: relative;
        color: #fff;
        font-size: 24px;
        font-weight: 600;
        letter-spacing: 5px;
        margin-bottom: 30px;
        cursor: pointer;
    }

    /* 登录标题的下划线样式 */
    .form h2::before {
        content: "";
        position: absolute;
        left: 0;
        bottom: -10px;
        width: 0px;
        height: 3px;
        background: #fff;
        transition: 0.5s;
    }

    .form h2:hover:before {
        width: 53px;
    }

    .form .inputBox {
        width: 100%;
        margin-top: 20px;
    }

    /* 输入框样式 */
    .form .inputBox input {
        width: 100%;
        padding: 10px 20px;
        background: rgba(255, 255, 255, 0.2);
        outline: none;
        border: none;
        border-radius: 30px;
        border: 1px solid rgba(255, 255, 255, 0.5);
        border-right: 1px solid rgba(255, 255, 255, 0.2);
        border-bottom: 1px solid rgba(255, 255, 255, 0.2);
        font-size: 16px;
        letter-spacing: 1px;
        color: #fff;
        box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    }

    .form .inputBox input::placeholder {
        color: #fff;
    }

    /* 登录按钮样式 */
    .form .inputBox input[type="button"] {
        background: #fff;
        color: #666;
        max-width: 100px;
        margin-top: 20px;
        margin-bottom: 20px;
        font-weight: 600;
        cursor: pointer;
    }

    .forget {
        margin-top: 6px;
        color: #fff;
        letter-spacing: 1px;
    }

    .forget a {
        color: #fff;
        font-weight: 600;
        text-decoration: none;
    }
</style>
